The present invention is directed to bicycles and, more particularly, to a bicycle crank assembly and to the components and tools used to assemble the bicycle crank assembly.
A bicycle bottom bracket is a cylindrical tube portion of the bicycle frame used to rotatably mount the pedal assembly to the bicycle. The pedal assembly usually comprises right and left crank arms, each of which has a pedal attached to one end. The other end of each crank arm is attached to an axle that extends through the bottom bracket. A bearing assembly is disposed between the axle and the bottom bracket at each side of the bottom bracket for rotatably supporting the axle, and one or more front sprockets usually are attached to the right side crank arm for driving the bicycle chain.
The front sprocket(s) must be properly aligned with the rear sprocket(s) attached to the rear wheel so that the bicycle operates properly. Thus, the axle must be properly positioned laterally within the bottom bracket. In one known technique for adjusting the lateral position of the axle, the axle is rotatably centered and laterally fixed within a tubular member by bearing assemblies installed at opposite ends of the tubular member. The axle and tubular member then are placed inside the bottom bracket. Adapter members having threaded outer peripheral surfaces are screwed into the threaded inner peripheral surface of the bottom bracket on opposite sides of the tubular member so that the lateral position of the axle is determined by how much of each adapter member is screwed into the bottom bracket. Unfortunately, since the adapter members must be long enough to accommodate many different lateral positions of the axle, usually a portion of the threaded outer peripheral surface of each adapter member is exposed, and this often results in rusting and dirt contamination of the threads. Also, since the axle is fixed to the tubular member through the bearing assemblies, the axle, tubular member and bearing assemblies ordinarily must be replaced as a unit.
The present invention is directed to a bicycle crank assembly wherein the lateral position of the axle may be adjusted without one or more of the disadvantages of prior art axle assemblies. In one embodiment of the present invention, a bicycle crank arm apparatus includes an axle having a first end portion and a second end portion, wherein the first end portion has an outer peripheral surface and a threaded inner peripheral surface; an axle bolt having a threaded outer peripheral surface screwed into the threaded inner peripheral surface of the first end portion of the axle; a crank arm having an axle mounting boss defining an opening for receiving the first end portion of the axle therein, wherein the axle mounting boss includes a first fastener for tightening the axle mounting boss around the first end portion of the axle; and wherein the crank arm boss is positioned axially inwardly of the axle bolt. At least one advantage of this structure is that the axle bolt may be used to laterally position the axle and the crank arms relative to each other, and the crank arm may be used to cover any threaded portion of the axle bolt that is not screwed into the axle.
In one embodiment of an axle bolt used to assembly the crank arm to the axle, an axle bolt includes a bolt body having a threaded outer peripheral surface and an inner peripheral surface defining an opening. A plurality of splines are circumferentially disposed on the inner peripheral surface of the bolt body, and a flange extends radially outwardly from the bolt body.
In one embodiment of a tool for screwing the axle bolt into the axle, the tool comprises a tool body, a plurality of splines circumferentially disposed on an outer peripheral surface of the tool body, and a tool operating member extending radially outwardly from the tool body.